This invention relates to a mat of the kind comprising a plurality of first strips of rigid, that is rigid or at least semi-rigid material, for example aluminium or plastics material such as polyvinylchloride or polypropylene, and a plurality of second strips of flexible material such as natural or synthetic rubber, interposed alternately between the first strips, the first and second strips being secured together in side-by-side relationship by means of one or more connecting elements, such as wires, which pass through aligned apertures in the first and second strips.
Previously, the first strips have been made of substantially H-configuration, the cross piece of the H in use, lying vertically, and having the apertures therein, the edges of the side pieces of the H abutting the adjacent flexible second strips. Such a mat is described in our previous U.K. Pat. No. 1,055,960.
The first strips have been made in H section so as to provide the necessary strength to withstand deformation when a load is imposed on the first strips, such as a person walking thereupon.
The apertures in the first and second strips have been made conveniently by punching as it has been found that a punching tool has a longer useful life than a drill, and punching is a quicker operation to perform than drilling.
Mats of the kind specified hitherto have been at least 1.7 centimeters thick. However, there is a long standing demand to provide a similar but thinner mat, for example, of substantially 1.2 centimeters deep. However, it has not been found possible hitherto to provide economically a mat of the type described of less than 1.7 centimeters depth merely by reducing the dimensions of the component parts of the known mats, for the following reasons.
To punch apertures in the cross piece of an H-configuration first strip, it is necessary to use a backing die to support the section on the opposite side of the cross piece to that which the punch enters, to prevent the strip from deforming. Thus, if the dimensions of the H-section first strips are reduced, it is not possible to insert such a backing die into the reduced space between the side pieces. If the apertures are punched in the cross piece, without a backing die, the section is damaged.
When making apertures in a second flexible strip, it was found that the strip burst in the region of the aperture during the punching operation when the thickness of the strip was reduced to that necessary to achieve the desired thinner mat. It has been found not possible to reduce the size of the connecting elements thereby permitting a reduction in the size of the apertures, since this results in a mat of inadequate strength being produced.
It is threfore an object of the present invention to provide a new and improved mat of the kind specified, and a method of making such a mat, which overcomes or reduces the above mentioned problems.